• Food Science of Animal Resources
• /
• v.29 no.1
• /
• pp.47-54
• /
• 2009

Predictive modeling was applied to study the growth of microorganisms related to spoilage in frankfurter sausage containing various levels of dietary fiber (0, 1, 2, and 3%) from rice bran and to estimate its shelf-life. Using the Baranyi model, total viable cells, anaerobic and psychrotrophic bacteria were measured during 35 days of cold storage ($<4{\pm}1^{\circ}C$). The lag times (LT) demonstrated by control and treatment groups were 6.28, 623, 6.24, and 6.25 days, respectively. The growth rate of total viable cells in each group were 0.95, 0.91, 0.92, and 0.91 (Log CFU/g/day), respectively. The anaerobic and psychrotrophic bacteria had lower initial ($y_0$) and maximal bacterial counts ($y_{max}$) than total viable cells. Also, the anaerobic and psychrotrophic bacteria possessed lower growth rate and longer lag time than total viable cells. The estimated shelf-life of frankfurter containing rice bran fiber by the growth rate of total viable cells was 7.8, 7.9, 7.9, and 7.7 days, respectively. There were no significant differences in shelf-life as a function of fiber content. In other words, the addition of dietary fiber in sausage did not show the critically hazardous results in growth of microorganism. The 12 predictive models were then characterized by high $R^2$, and small RMSE. Furthermore, $B_f$ and $A_f$ values showed a very close relationship between the predictive and observed data.

• ETRI Journal
• /
• v.38 no.4
• /
• pp.622-633
• /
• 2016

A discontinuous reception (DRX) operation is included in the Long Term Evolution (LTE) system to achieve power saving and prolonged battery life of the user equipment. An improvement in DRX power saving usually leads to a potential increase in the packet delay. An optimum DRX configuration depends on the current traffic, which is not easy to estimate accurately, particularly for non-real-time applications. In this paper, we propose a novel way to vary the DRX cycle length, avoiding a continuous estimation of the data traffic when only non-real-time applications are running with no active real-time applications. Because a small delay in non-real-time traffic does not essentially impact the user's experience adversely, we deliberately allow a limited amount of delay in our proposal to attain a significant improvement in power saving. Our proposal also improves the delay in service resumption after a long period of inactivity. We use a stochastic analysis assuming an M/G/1 queue to validate this improvement.

• Earthquakes and Structures
• /
• v.24 no.4
• /
• pp.303-316
• /
• 2023

Rapid post-earthquake damage estimation of subway stations is particularly necessary to improve short-term crisis management and safety measures of urban subway systems after a destructive earthquake. The conventional Performance-Based Earthquake Engineering (PBEE) framework with constant earthquake occurrence rate is invalid to estimate the aftershock risk because of the time-varying rate of aftershocks and the uncertainty of mainshock-damaged state before the occurrence of aftershocks. This study presents a time-varying probabilistic seismic risk assessment framework for underground structures considering mainshock and aftershock hazards. A discrete non-omogeneous Markov process is adopted to quantify the time-varying nature of aftershock hazard and the uncertainties of structural damage states following mainshock. The time-varying seismic risk of a typical rectangular frame subway station is assessed under mainshock-only (MS) hazard and mainshock-aftershock (MSAS) hazard. The results show that the probabilities of exceeding same limit states over the service life under MSAS hazard are larger than the values under MS hazard. For the same probability of exceedance, the higher response demands are found when aftershocks are considered. As the severity of damage state for the station structure increases, the difference of the probability of exceedance increases when aftershocks are considered. PSDR=1.0% is used as the collapse prevention performance criteria for the subway station is reasonable for both the MS hazard and MSAS hazard. However, if the effect of aftershock hazard is neglected, it can significantly underestimate the response demands and the uncertainties of potential damage states for the subway station over the service life.

• Journal of the Society of Disaster Information
• /
• v.11 no.4
• /
• pp.548-555
• /
• 2015

This paper aims to estimate the service life of the target bridge structures subjected to chloride ingress from de-icer, which is used for safety of vehicles in winter, by investigating the chloride ingress into concrete. In this study, the 10-year-old bridge structures were investigated by measuring the chloride along the depth from the exposed surface to derive the surface chloride concentration and the diffusion coefficient for the prediction of service life. The service life of each measured point on the structures were estimated with the surface chloride concentration and the diffusion coefficient by using Life-365 software. As a result, it was estimated for all measured points to have over 100-year service life. Furthermore, the diffusion coefficient and the service life from the measured data were compared to another method calculated with the concrete mix, considering the time dependency of diffusion coefficient.

• Journal of Korean Society for Quality Management
• /
• v.34 no.3
• /
• pp.19-30
• /
• 2006

For highly reliable products, it is difficult to assess the lifetime of the products with traditional life tests. Accordingly, a recent approach is to observe the performance degradation of product during the test rather than regular failure time. This study compares performances of three methods(i.e. the approximation, analytical and numerical methods) to estimate the parameters and quantiles of the lifetime when the time-to-failure distribution follows Weibull and lognormal distributions under a random coefficient degradation rate model. Numerical experiments are also conducted to investigate the effects of model error such as measurements in a random coefficient model.

• The Transactions of the Korean Institute of Electrical Engineers P
• /
• v.59 no.4
• /
• pp.372-376
• /
• 2010

Electrolytic capacitors have been widely used in power electronics system because of the features of large capacitance, small size, high-voltage, and low-cost. Electrolytic capacitors, which is most of the time affected by aging effect, plays a very important role for the power electronics system quality and reliability. Therefore it is important to estimate the parameter of an electrolytic capacitor to predict the failure. The estimation of the equivalent series resistance(ESR) is important parameter in life condition monitoring of electrolytic capacitor. This paper proposes a simple technique to measure the ESR of an electrolytic capacitor. This method uses a switching DC/DC boost converter to measure the DC Bus capacitor ESR of power converter. Main advantage of the proposed method is very simple in technique, consumes very little time and requires only simple instruments. Simulation results are shown to verify the performance of the proposed method.

• Journal of the Society of Naval Architects of Korea
• /
• v.46 no.5
• /
• pp.510-519
• /
• 2009

Ship structure is composed of the welded mixture members which are plate and stiffeners. Ship structure is also influenced by variable loadings such as wave and inertia load. There have been several fatigue damage problems on the connection between longitudinal and transverse web due to wide usage of high tensile steel and adoption of wide web space to improve shipbuilding productivity. It is impossible to estimate the fatigue lives for all connection details through refined fatigue analysis. It is necessary to use the simplified approach for the fatigue life estimation of the connection details. PLUS analysis, which is suggested by the classification society, is one of the simplified approaches and is widely adopted to get fatigue lives for the connection details along whole cargo hold area. However, ship building yards still have difficulties to get fatigue lives due to large amount of calculation and time even if this approach reduce the time and amount of calculation. This paper treats the computing system developed to reduce efforts of estimating the fatigue lives. The influence factors of mean shear stress and local dynamic pressure are easily calculated and fatigue lives for all hot spots can be estimated automatically by the developed computing system. It is possible to reduce computing time and efforts to get the fatigue lives for the connection details between longitudinals and transverse webs along the ship. This system was applied to get fatigue lives on the connection details of a VLCC and verified the availability.

• Journal of the Korea Institute of Information and Communication Engineering
• /
• v.19 no.6
• /
• pp.1419-1435
• /
• 2015

In this study an active RFID system of low power consumption is proposed, for which we improved the tag collection algorithm of ISO/IEC 18000-7 standard and significantly reduced the tag collection time. We classified the type of power consumption according to the operating mode of active RFID and proposed the method which can accurately estimate battery life time. By calculating the power consumptions of proposed and current methods, we can compare the battery life times of both methods. Through this analysis we can demonstrate the superiority of the proposed method in battery life time.

• Journal of Microbiology and Biotechnology
• /
• v.17 no.7
• /
• pp.1221-1225
• /
• 2007

A ${\beta}$-ionone-resistant mutant strain isolated from the red yeast Xanthophyllomyces dendrorhous KCTC 7704 was used for batch and continuous fermentation kinetic studies with glucose media in a 2.5-1 jar fermentor at $22^{\circ}C$ and pH 4.5. The kinetic pattern of growth and carotenoid concentration in the batch fermentations exhibited a so-called mixed-growth-associated product formation, possibly due to the fact that the content of intracellular carotenoids depends on the degree of physical maturation toward adulthood. To determine the maximum specific growth rate constant (${\mu}_m$) and Monod constant ($K_s$) for the mutant, glucose-limited continuous culture studies were performed at different dilution rates within a range of $0.02-0.10\;h^{-1}$. A reciprocal plot of the steady-state data (viz., reciprocal of glucose concentration versus residence time) obtained from continuous culture experiments was used to estimate a ${\mu}_m$ of $0.15\;h^{-1}$ and $k_s$ of 1.19 g/l. The carotenoid content related to the residence time appeared to assume a typical form of saturation kinetics. The maximum carotenoid content ($X_m$) for the mutant was estimated to be $1.04\;{\mu}g/mg$ dry cell weight, and the Lee constant ($k_m$), which was tentatively defined in this work, was found to be 3.0 h.

• Journal of Convergence Society for SMB
• /
• v.2 no.1
• /
• pp.19-24
• /
• 2012

In this paper, we propose the battery life time extension method in the multi-interface terminal by using the state information in an optical wireless integrated network architecture. When the bottlenecks occurs in the network, the terminal receives data packets via multipath. However, the battery life time is rapidly reduced because the power consumption of the terminal is bigger than single interface. For reducing the power consumption in the multi-interface terminal, the Optical Line Terminal (OLT) confirms whether the bottleneck phenomenon is occurred or not. And the network state information is transmitted to the terminal. The terminal turns one of the interfaces off to reduce the power consumption. In order to estimate the performance, we compare the power consumption between single and dual interfaces.